1. Field of the Invention
The present invention relates to a mixing apparatus for mixing a liquid in a vessel. More particularly, it relates to a mixing apparatus utilized for well mixing of a liquid sample and a liquid reagent contained in a vessel in an automatic analyzer.
2. Description of the Related Arts
Conventionally, an automatic analyzer, such as a blood coagulation measuring apparatus for measuring the coagulability of blood, involves mixing of a subject liquid sample (plasma) and a liquid reagent in a vessel.
Known apparatus for mixing a liquid in a vessel are, for example, one which allows the liquid to be discharged into the vessel and makes use of the discharging pressure for mixing (Apparatus A), one which allows a bar-like member to be inserted into the vessel containing the liquid and utilizes the bar-like member for mixing (Apparatus B), and one which allows an eccentric rotational movement of the vessel containing the liquid for mixing (Apparatus C) as disclosed in Japanese Examined Utility Model Publication No. Hei. 5(1993)-9069.
Apparatus A is liable to cause mixing nonuniformity because it utilizes discharging pressure. Apparatus B necessitates washing of the bar-like member every time the mixing is conducted and, moreover, when the washing is insufficient, it may possibly cause mutual contamination of liquids. Apparatus C has a drawback that it tends to be large and mechanically complicated. Moreover, there is a problem of control that the driving source such as the motor must be stopped at a predetermined position to place the vessel at a prescribed location after the mixing.